UC San Diego

Gas processing facilities, where gas is received and treated, provide motivation and embodiment for the development of systematic control-oriented modeling tools suited to the design of process control solutions based on plant schematics and layouts. The control of these plants involves the interconnection of a number of elements including pipes, compressors, heat exchangers, valves and valve manifolds, and other process units and volumes. The goal of this work is to provide a systematic, scalable and reconfigurable modeling methodology eventually used for process control of such gas-handling facilities at nominal operation. We aim to simplify the control design so that it appeals to generalists without deep expertise in control of fluid flow, using software tools such as Simulink/Matlab and Python. We provide control-oriented component models of standard equipment incl. pipe intersections, compressors, valves and heat exchangers, which serve as modules for entire networks. By exploiting the index-1 property of systems of differential algebraic equations that naturally arise for interconnections our composite LTI state-space models subsume algebraic equations; hence, control-orientation. We also show that for networks conservation of mass is inherited by its components and leads to an integrator in the pressure channel with important implications for control design. The Matlab code provided in the Appendix corroborates the suitability of our approach for software-based control design.